This invention relates to an image processing apparatus which processes data for a color image for display by a display device, such as a liquid crystal display.
Such liquid crystal displays are as display devices in personal computers, word processors or televisions and the like.
The use of a bistable liquid crystal element has been proposed by Clark and Lagerwall (U.S. Pat. No. 4,367,924). Ferroelectric liquid crystal having Chiral smectic C phase (Sm C *) or H phase (Sm H *) is usually used as the bistable liquid crystal. This liquid crystal has bistable states in the absence of an electric field, including a first optically stable state (first orientation state) and a second optically stable state (second orientation state). Accordingly, unlike an optical modulation element used in a TN (twist nematic) type liquid crystal, the liquid crystal is oriented stably in the first optically stable state by one electric field vector, and the liquid crystal is oriented stably in the second optically stable state by the other electric field vector.
The liquid crystal of this type quickly responds to the applied electric field to assume one of the two stable states and maintains the state when the electric field is removed.
However, the bistable liquid crystal element has only two states, so a liquid crystal display which consists of such bistable liquid crystal cells cannot display a halftone image or a full color image.